Bilinear damage evolution in AA2011 wire drawing processes

This paper presents an experimental and numerical analysis of damage evolution in AA2011 aluminum alloy wires drawn under different scenarios. To this end, load-unload tensile tests were firstly carried out in order to characterize the degradation of the mechanical response in every cycle where the experimental results show a bilinear damage relationship in terms of the effective plastic strain. Therefore, a modification of the classical Lemaitre model is proposed in this work in order to reproduce bilinear paths of damage with the addition of only two parameters that can be directly obtained from the material characterization. Then, the damage predictive capability of this new experimental-based model is assessed in numerical simulations of the drawing process in one and two passes (considering for this last case the sequential and tandem configurations) where the computed predictions are compared with the corresponding experimental data showing a good agreement between them.

Choice of a method of carbon wire drawing

At present for wire production various methods of drawing are used. To choose an effective drawing method or their combination, a methodology is needed to estimate existing and new methods of drawing. A methodology of simultaneous estimation of strain-stress state of carbon wire in the area of deformation and force conditions of drawing presented. Based on it an analysis of drawing in monolith dies, roller dies of radial-shear broach, classic two- and multi-roller dies was carried out. A module-combined method of drawing was also considered. Recommended modes of reduction for drawing in monolith dies presented. It was shown that to obtain a wire of 4.0 mm diameter max, the drawing in monolith dies is most effective. For production of wire of larger diameters, roller dies are more advisable. Application of the technology of radial-shear deformation enables to obtain a fine-grained structure in the surface layers of wire. It was shown that application of a module comprising a roller die and a monolith die is most effective. An example of drawing of a round wire from 8.0 mm diameter to 3.0 mm diameter by a route developed with their application considered. Recommendations on application of various methods of drawing for wires of diameter from 0.007 mm to 15.0 mm presented.

Features of diseases of the musculoskeletal and peripheral nervous systems in workers of metallurgical production in modern conditions

Manufacturing industries, including metallurgy, are the backbone of the country’s economy. A number of technological operations involve the impact of physical overload, heating microclimate, static load, and often entails the development of diseases of the musculoskeletal and peripheral nervous systems. The clinical picture of such patients is dominated by pain in various parts of the spinal column, in some cases, combined localization. The analysis of the results of the examination of the connection of diseases of the musculoskeletal and peripheral nervous systems with the profession, carried out by employees of a large metallurgical enterprise of the Republic of Bashkortostan (RB), using the archival material of the FBUN clinic «Ufa Research Institute of Occupational Medicine and Human Ecology» was carried out. The group of the main professions of the enterprise includes: wire drawing machine, wire rewinder, caliper, pyrometrist, laboratory assistant for physical and mechanical tests, automatic machine for cold landing machines, mechanic-repairman, sorter-delivery of metal. During the analyzed period, in 117 cases, the workers of the enterprise confirmed the professional etiology of the disease. The nosological structure in 60 % of cases of the first established occupational diseases is represented by diseases of the musculoskeletal system and connective tissue. A significant part of diseases of occupational etiology was detected in persons aged 50 to 59 years. Workers of the studied professional groups are at the highest risk of developing diseases of the musculoskeletal and peripheral nervous systems of professional etiology, which is due to the specific conditions of their professional activity. Establishing a connection between the disease and the profession is characterized by late detection, at the stage of pronounced clinical symptoms with the formation of persistent disability.

External Surface Quality of the Graphite Crystallizer as a Factor Influencing the Temperature of the Continuous Casting Process of ETP Grade Copper

Today’s world is a place where lack of electrical energy would be unimaginable for most of society. All the conductors in the world, both aluminum and copper, have their origin in various types of casting lines where the liquid metal after crystallization is being processed into the form of wires and microwires. However, the efficiency of the continuous casting processes of metals and the final quality of the manufactured product strictly depend on the design of the used crystallizers, the materials used during its production and its quality. Research conducted in this paper focuses on the latter, i.e., external surface quality of the graphite crystallizer at the place of contact with the primary cooling system. In order to quantify its influence on the continuous casting process numerical analyses using the finite element method has been conducted, which results have been further confirmed during empirical tests in laboratory conditions. It has been proven with all of the proposed methods that the temperature of the obtained cast rod is closely linked to the aforementioned surface quality, as when its roughness coefficient surpasses a certain value the temperature of the obtained product increases almost twofold from approx. 150–170 °C to 300–320 °C. These values might influence the quality and final properties of the cast rod, the susceptibility to wire drawing process and possible formation of wire drawing defects and therefore be of much importance to the casting and processing industry.

Characterization of AlSi10Mg-CP-Ti Metal/Metal Composite Materials Produced by Electro-Sinter-Forging

Metal–metal composites represent a particular class of materials showing innovative mechanical and electrical properties. Conventionally, such materials are produced by severely plastically deforming two ductile phases via rolling or extruding, swaging, and wire drawing. This study presents the feasibility of producing metal–metal composites via a capacitive discharge-assisted sintering process named electro-sinter-forging. Two different metal–metal composites with CP-Ti/AlSi10Mg ratios (20/80 and 80/20 vol.%) are evaluated, and the effects of the starting compositions on the microstructural and compositional properties of the materials are presented. Bi-phasic metal–metal composites constituted by isolated α-Ti and AlSi10Mg domains with a microhardness of 113 ± 13 HV0.025 for the Ti20-AlSi and 244 ± 35 HV0.025 for the Ti80-AlSi are produced. The effect of the applied current is crucial to obtain high theoretical density, but too high currents may result in Ti dissolution in the Ti80-AlSi composite. Massive phase transformations due to the formation of AlTiSi-based intermetallic compounds are observed through thermal analysis and confirmed by morphological and compositional observation. Finally, a possible explanation for the mechanisms regulating densification is proposed accounting for current and pressure synergistic effects.

Characterization of AlSi10Mg- CP-Ti Metal-metal Composite Materials Produced by Electro-sinter-forging

Metal/metal composites represent a particular class of materials showing innovative mechanical and electrical properties. Conventionally, such materials are produced by severely plastically deforming two ductile phases via rolling or extruding, swaging, and wire drawing. This study presents the feasibility of producing metal/metal composites via a capacitive discharge-assisted sintering process named electro-sinter-forging. Two different metal/metal composites with CP-Ti/AlSi10Mg ratios (20/80 and 80/20 %vol) are evaluated, and the effects of the starting compositions on the microstructural and compositional properties of the materials are presented. Bi-phasic metal/metal composites constituted by isolated α-Ti and AlSi10Mg domains with a microhardness of 113 ± 13 HV0.025 for the Ti20-AlSi and 244 ± 35 HV0.025 for the Ti80-AlSi are produced. The effect of the applied current is crucial to obtain high theoretical density, but too high currents may result in Ti dissolution in the Ti80-AlSi composite. Massive phase transformations due to the formation of AlTiSi based intermetallic compounds are observed through thermal analysis and confirmed by morphological and compositional observation. Finally, a possible explanation for the mechanisms regulating densification is proposed accounting for current and pressure synergistic effects.

Modern state and directions of perfection of technological processes of manufacturing hardened-tempered spring wire

Hardened-tempered spring wire has a great demand in domestic automobile industry. A considerable part of such a wire is imported. In view of increase of demand in treated wire for springs of critical application and measures implementation for import substitution, perfection of technological processes of its production becomes actual. Basic technical requirements to spring wire as per domestic and foreign standards presented, the factors effecting the quality of finished products considered. Description of technological processes of hardened-tempered spring wire of critical application presented. It was shown that domestic technological scheme of treated wire production is analogous to foreign one, however to reach the quality of products, correspondent to norms нормам EN 10270-2:2012, a perfection of it is needed. Proposals to improve the technology of manufacturing domestic competitive products elaborated. Among them a necessity to use steels of Si‒Cr or Si‒Cr‒V system, additionally alloyed by manganese, cobalt, tungsten a(or) other elements highlighted. It was proposed to implement an operation of scalping instead of turning and a system of nondestructive control, to use resource-saving routes of wire drawing with high uniformity of properties, to replace hardening and tempering by thermomechanical treatment (for some kinds of wire), to use modern highly-productive equipment.

COMPARATIVE STUDIES OF THE SUSCEPTIBILITY OF COPPER AND ALUMINUM TO PROCESSING IN WIRE DRAWING PROCESS

Modern technological solutions in electrical applications require, above all, high energy efficiency. This means that in such applications, materials with the highest possible electrical conductivity should be used for conductive elements. Of all metals, copper is the natural choice. Copper cables or wires used in electrical networks and installations provide better electrical and thermal conductivity and guarantee reliability - which translates into the quality of electricity. And bad quality of energy means tangible financial losses. On the other hand, apart from physical properties, an important factor is the price of cables and wires, which is partially dependent on the price of copper on the stock exchange. The last 20 years have seen a high increase in copper prices on the markets and at the same time the price is unstable. Therefore, cheaper substitutes for copper are being sought. The natural choice is aluminum, which is currently widely used in overhead power lines. At the same time, in the case of long cables, copper products still dominate. The paper presents a synthetic comparative analysis of technological processing problems in industrial drawing processes of aluminum and copper wires used in electrical applications.. In particular, comparative analysis applied the susceptibility into formability in the wire drawing process and susceptibility to recrystallization annealing of copper and aluminum wires. The drawing process and the annealing process are simple processes for the production of wires used for electrical purposes.

Novel drawing system approach to manufacture performant commercially pure aluminium fine wires

Due to its electro-mechanical properties, commercially pure aluminium wires have attracted the interest of automotive industry representing a functional and efficient economic solution to reduce vehicle’s weight leading to the diminishing of energy consumption and emissions in today’s society. However, to consolidate its use in this sector and in new market realities, it is necessary to increase the flexibility of the aluminium conductor wires, consenting their installation in very small spaces and with high curvatures, avoiding any failure and electrical conductivity decrease. Thus, the evolution of microstructure and service performance needs to be investigated and controlled to improve the service safety. The present research shows a new approach to continuously manufacture efficient long wires with smaller diameters and fine grains at room temperature. It is studied the strengthening effects (yield and tensile strength, plasticity, hardness), the electrical conductivity, and the microstructural changes of commercial 1370 pure aluminium (99.7% Al) when traditional wire drawing process is combined with equal channel angular drawing (ECAD) technique. The results of this proposed procedure of deformation “drawing-ECAD-drawing” show an evident benefit, compared to the classic technology of production of aluminium wire, obtaining fine grain structure product with superior mechanical strength and not influenced electrical conductivity. The proposed manufacturing approach leads to fine wires enhancing the material mechanical properties by microstructural evolution (i.e. grain size reduction) avoiding the traditional post manufacturing thermal treatments requiring a high amount of energy and time and careful steps.